Internal combustion engine exhaust gas controlling device

ABSTRACT

An internal combustion engine exhaust gas controlling device which operates a solenoid valve in response to a predetermined value of the car speed driven by the engine, said solenoid valve being operative to communicate a throttle valve mechanism of a carburetor of said engine to an atmospheric pressure circuit and simultaneously a vacuum retard diaphragm unit for a distributor with a vacuum circuit conducted to a suction manifold of said engine when the vehicle speed exceeds a predetermined value, whereby the vacuum produced at deceleration of the vehicle is utilized to automatically operate the distributor vacuum retard diaphragm to retard spark timing and the atmospheric pressure communicated to the throttle valve mechanism operates to prevent the throttle value from complete closure in case the vehicle is decelerated from the speed above said predetermined value thereby to greatly reduce the exhaust of noxious gas from the internal combustion engine.

United States Patent Okada 1451Marcl1 20, 1973 [54] INTERNAL COMBUSTION ENGINE 3,410,362 11/1968 Fales ..123/102 EXHAUST GAS CONTROLLING DEVICE Primary Examiner-Laurence M. Goodridge Assistant Examiner-Ronald B. Cox [75] Inventor: Masashi Okada, Kanya, Japan Attorney cushman, Darby & Cushman [73] Assignee: Nippondenso Kabushiki Kaisha,

Aichi-Ken, Japan [5 7] ABSTRACT [22] Filed. 27 1970 An internal combustion engine exhaust gas controlling device which operates a solenoid valve in response to [2]] Appl. No.: 14,968 a predetermined value of the car speed driven by the engine, said solenoid valve being operative to communicate a throttle valve mechanism of a carburetor of [30] Forelgn Apphcamm Pnonty Data said engine to an atmospheric pressure circuit and April 9, 1969 Japan ..44/32342 simultaneously a vacuum retard diaphragm unit for a distributor with a vacuum circuit conducted to a suc- [52] US. Cl... "123/97 B, 123/117 R, 123/117 A, tion manifold of said engine when the vehicle speed 180/105 exceeds a predetermined value, whereby the vacuum 51 Int. Cl. ..F02d 31 00, F02p 5/04 produced at deceleration of the vehicle is utilized to [58] Field of Search ..123/117.1, 117,97 B, 102; eytematieally Operate the fiistributer vacuum retard 1 0 05 10 107 10 09 110 diaphragm to retard spark timing and the atmospheric pressure communicated to the throttle valve 56] References Cited mechanism operates to prevent the throttle value from complete closure in case the vehicle is decelerated UNIT ED STATES PATENTS from the speed above said predetermined value thereby to greatly reduce the exhaust of noxious gas Toda from the internal combustion engine- 2,886,020 5/1959 ..l23/97 B 1 Claim, 2 Drawlng Figures 3,272,191 9/1966 ....l23/1l7.l 3,289,659 12/1966 l23/l17.l

C141? SPEED SW/TCH/NG 0575mm REL MA mew/r5775? SEW/0N SECT/O/V W V5 VACUUM RE 721/?!) DMPH/PAGM U/V/7' INTERNAL COMBUSTION ENGINE EXHAUST GAS CONTROLLING DEVICE BACKGROUND OF THE INvENTIoN FIELD OF THE INvENTIoN This invention relates to an internal combustion engine exhaust gas controlling device which controls the exhaust gases through detection of the car speed driven by the engine.

SUMMARY OF THE INVENTION An object of the invention is to provide an exhaust gas controlling device comprising a generator capable of generating a voltage representative of the speed of the car, a switching-relay section including a transistor amplifier circuit for detecting if the voltage generated by the generator has reached a predetermined value, and a magnet valve controlled by the switching-relay section, the magnet valve effecting change-over between the negative-pressure circuits communicated with a throttle valve mechanism of a carburettor and with the vacuum retard diaphragm unit for a distributor.

In accordance with the invention, upon the speed reduction of the car, the throttle valve of the carburettor is opened slightly larger than the idling opening, while the ignition timing is delayed. Thus, the invention has advantages in that the noxious gas, which otherwise may be much exhausted at deceleration of the car due to an engine misfiring etc. is remarkably decreased without decreasing the braking effect of the engine.

In addition, since the preset car speed is detected from the voltage produced by the generator in response to the speed of the car by means of the transistor amplifier circuit possible to detect the preset car speed. The invention is advantages in that the preset car speed is not only accurately detected, but readily changeable by changing the circuit constants of the transistor amplifier circuit.

In accordance with the invention, the switching relay section may further comprise a second transistor having a collector-emitter circuit connected across the base-emitter circuit of said power transistor through said first constant-voltage element and having a base connected to a second constant-voltage element having an operating voltage higher than that of said first constant-voltage element, said second constant-voltage element being connected in series with a second bias resistor to the collector of said power transistor and also connected in series with a first diode to the collector of said first transistor, and comprises a second diode connected between the collect of saidfirst transistor and said first constant-voltage element. Therefore, the invention further has an excellent advantage in that during normal operation the solenoid valve is controlled in accordance with an input signal by means of the power transistor, but in case of an accidental shortcircuit of the solenoid valve under the conductive condition of the power transistor, the power transistor is immediately rendered non-conductive by the second transistor, thereby to prevent the power transistor from being damaged from an overcurrent due to the shortcircuit.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an exhaust gas controlling device according to the invention.

FIG. 2 is an electrical connection diagram of an electric control section including a car-speed detection section, of the device of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Description will now be made of an embodiment shown in the accompanying drawings. FIG. 1 is a block diagram of a device according to the invention. In the figure, the reference numeral 1 designates a car-speed detection section, 2 a switching-relay section actuated in response to the detected car-speed, and 3 a solenoid valve which is actuated by the output of the switchingrelay section 2 and which effects the change of the connections of atmospheric-pressure and vacuum circuits. At 4 is indicated a carburettor while at 4' a vacuum retard diaphragm unit for a distributor, both of which are adapted to be driven responsive to vacuum introduced through the negative pressure circuit which in turn is controlled by the solenoid valve 3. Referring now to FIG. 2, a generator 5 constituting the car-speed detecting section 1 is coupled to a rotary shaft responsive to the car speed, e.g., the cable of a speed-meter, and thereby generates a voltage corresponding to the car speed. Numeral 6 represents a full-wave rectifier of the bridge type, and numeral 7 indicates a smoothing condenser. Numerals 8 and 9 designate resistors for voltage division, while numerals 13 and 14 indicate transistors for constituting a Schmitt circuit. Numerals 15, 16 and 17 designate resistors, respectively. Shown at 18 is a common emitter resistor for the Schmitt circuit, and at 19 and 20 respectively are transistors. Numeral 21 indicates a bias resistor. Numerals 22, 23, 24 and 25 respectively represent diodes, among which those of numerals 23 and 25 are Zener diodes. Shown by numerals 26 and 27 are a power switch and a power supply battery, respectively.

The operation of the device of the above arrangement will now be explained. The generator 5 generates an AC output voltage corresponding to the speed of the car. The output voltage of the generator 5 is rectified by the full-wave rectifier 6 and smoothed by the condenser 7. As a result, a DC voltage corresponding to the car speed is produced across the resistor 9. At a low running speed of the car, e.g., lower than approximately 20 Km/h, the voltage across the resistor 9 is low so that the base current supplied to the transistor 9 is not sufficient to hold it conductive, and hence the transistor 13 is rendered non-conductive. Consequently, the transistor 14 is supplied with a base current through the bias resistors 15 and 16 thereby to be rendered conductive. As a result, the electric potential at a connection point A on the cathode side of the Zener diode 23 approaches the ground potential through the diode 22 and the collector-emitter circuit of the transistor 14, so that there is not sufficient potential to render the Zener diode 23 operative, and hence the power transistor 19 becomes non-conductive. This will shut off the solenoid valve 3 from the power thereby to bring it to an inoperative condition. In this case, the non-conductive state of the power transistor 19 raises the collector potential of the power transistor 19, but the diode 24 interposed between the collector of the transistor 14 and the cathode of the Zener diode 25, prevents a current flow from the collector of the power transistor to the base of the transistor 14 and only a small current flows from the collector of the power transistor 19 through the resistor 21 and the diode 24 to the collector-emitter circuit of the transistor 14. Accordingly, the transistor is not rendered conductive.

On the other hand, upon the previously-mentioned deenergizing of the solenoid valve 3, the vacuum retard diaphragm unit 4' for the distributor is supplied with atmospheric pressure, thereby becoming deactuated. At the same time, throttle valve mechanism of the carburettor is fed with vacuum, so that the carburettor 4 becomes actuated such that the throttle valve may be freely movable. In other words when the carburetor has been conducted to vacuum, it operates without the restriction as to its idling position, which restriction is discussed below. Therefore, a sufficient throttling of the throttle valve will provide an desired number of idling rotations of the engine.

Thereafter, when the running speed of the car is raised to a certain preset value, e.g., approximately 20 km/h, the transistor 13 will be rendered conductive on account of an increase in the voltage across the resistor 9. This results in making the collector-emitter voltage of the transistor 13 substantially zero, whereupon the base and emitter of the transistor 14 are short-circuited thereby bringing the transistor 14 to the cutoff state. Accordingly, the power transistor 19 is supplied with a base current through the bias resistor 17 and the Zener diode 23, and is thereby rendered operative. As a result, the solenoid valve 3 is supplied with a current from the power source 27 through the collector-emitter circuit of the power transistor 19, whereby said solenoid valve 3 is energized. At this moment, the base and emitter of the transistor 20 are short-circuited due to the conduction of the power transistor 19, while the transistor 20 remains non-conductive. Therefore, the transistor 20 has no influence upon the operation of the control circuit. lncidently, it is necessary that the Zener voltage of the Zener diode 23 be selected lower than that of the Zener diode 25.

As previously described, upon the energizing of the solenoid valve 3, the throttle valve mechanism of the carburettor 4 is conducted to the atmospheric pressure, thereby restricting the motion of the throttle valve to a position greater than a normal idling opening if the accelerator pedal has been released. Further with valve 3 energized the vacuum retard diaphragm unit 4 for the distributor is conducted to vacuum. Under these conditions, the throttle valve mechanism is forced, due to the inflow of the atmospheric pressure, to provide a throttle valve opening slightly larger than the idling opening. However,. since the accelerator pedal is forcibly depressed during normal running by the driver, the slightly larger opening of the throttle valve mechanism will cause no trouble on the normal running. In addition, at the normal running the vacuum produced in the suction manifold of the engine is small, and hence the vacuum retard diaphragm unit 4 for the distributor is unopcrative, so that the ignition timing is not changed.

When the driver has released his foot from the accelerator pedal in order to decelerate the car from a high-speed running condition, the throttle valve of the carburettor 4 is urged to be closed. But, since the valve is opened slightly larger than the opening required for idling by means of the throttle valve mechanism, the amount of suction of the mixture in the engine is increased. The engine is thereby prevented from mis-firing during deceleration of the car and accordingly release of noxious gases due to such misfiring.

Furthermore, since the opening degree of the throttle valve is reduced at deceleration, a large higher vacuum is generated in the suction manifold of the engine so that the vacuum type ignition timing retardation device 4' for the distributor effects to retard the igni tion timing thereby to to ensure the braking effect of the engine which otherwise may reduce due to the slightly larger opening of the throttle valve of the carburettor 4.

The delay of the ignition timing at deceleration improves the combustion condition of the mixed gas thereby to raise the temperature of the exhaust gas, which further reduces exhaust of the noxious gas.

Thus, the exhaust of the noxious gas during the deceleration of the car may be remarkably decreased.

A further description will now be made of the circuit operation of the switching-relay section 2. When the transistor 13 is in the conductive state, the transistor 14 in the non-conductive state, and the power transistor 19 in the conductive state. When the solenoid valve 3 is short-circuited by accident, the power supply is directly connected across the collector and emitter of the power transistor 19, and the collector potential of the transistor reaches the power supply voltage. Therefore, the transistor 20 is supplied with a base current through A the resistor 21 as well as the Zener diode 25, whereby the transistor 20 is rendered conductive in a moment. This will short-circuit the base-emitter circuit of the power transistor 19 by means of the transistor 20, and hence the power transistor 19 is rendered non-conductive, even when the transistor 14 is in the cutoff state. Accordingly, even if the solenoid valve 3 be short-circuited, the power transistor 19 can be prevented from damage due to duration of an over-current which otherwise may be derived from the shortcircuit. At this time, the diode 22 serves to prevent a base current supplied to the transistor 19 through the diode 24 and the zener diode 23, so that the power transistor 19 is not rendered conductive even though the zener diode 25 and consequently the transistor 20 are not yet rendered conductive.

In the above embodiment, the Zener diodes 23 and 25 connected into the respective base circuits of the transistors 19 and 20 may be replaced, if necessary, with a plurality of diodes connected in series.

I claim:

1. An exhaust gas controlling device for an internal combustion engine having an accelerator, a carburetor throttle valve mechanism, a distributor vacuum retard diaphragm unit, an atmospheric pressure circuit and a suction manifold with a vacuum circuit, comprising:

a generator for producing an output voltage corresponding to the speed of a vehicle driven by said engine,

means including a solenoid valve having a first condition for communicating said vacuum circuit to said throttle valve mechanism while concurrently communicating the atmospheric pressure circuit to said vacuum retard diaphragm unit and a second condition for effecting vice versa communication of said circuits, and

a switching relay section for operating said solenoid valve in response to a predetermined value of said output voltage of said generator so as to cause said solenoid valve to be in said first condition for vehicle speeds below a given speed that correspondings to said predetermined output voltage and whereby ignition retard is prevented by said vacuum retard unit being thereby communicated to said atmospheric pressure circuit and the throttle valve of said mechanism is fully closed when said vehicle accelerator is fully released, and so as to cause said valve to be in said second condition for vehicle speeds above that corresponding to said predetermined output voltage, to reduce said given speed so that during vehicle deceleration from speeds above said given speed the vacuum produced in said vacuum circuit and communicated as aforesaid to said vacuum retard unit causes ignition retard while the said communication of the throttle valve mechanism to said atmospheric pressure circuit prevents said throttle valve from full closure, thereby substantially reducing nixious gases generated particularly during vehicle deceleration,

said switching relay section comprising a power transistor having a collector-emitter circuit connected in series with said solenoid valve,

a bias resistor a second transistor having a collector-emitter circuit connected in series with said bias resistor and responsive to said predetermined value of said output voltage of said generator, I

and a constant-voltage element having a predetermined operating voltage and connected between the base of said power transistor and the collector of said second transistor,

wherein said switching relay section further comprises a third transistor having a collector-emitter circuit connected across the base-emitter circuit of said power transistor through said constant-voltage element,

a second constant-voltage element connected to the base of said third transistor and having an operating voltage higher than that of the first mentioned constant-voltage element,

a second bias resistor and a first diode,

said second constant-voltage element being connected in series with said second bias resistor to the collector of said power transistor and also being connected in series with said first diode to the collector of said second transistor there being a second diode connected between the collector of said second transistor and said first mentioned constant-voltage element. 

1. An exhaust gas controlling device for an internal combustion engine having an accelerator, a carburetor throttle valve mechanism, a distributor vacuum retard diaphragm unit, an atmospheric pressure circuit and a suction manifold with a vacuum circuit, comprising: a generator for producing an output voltage corresponding to the speed of a vehicle driven by said engine, means including a solenoid valve having a first condition for communicating said vacuum circuit to said throttle valve mechanism while concurrently communicating the atmospheric pressure circuit to said vacuum retard diaphragm unit and a second condition for effecting vice versa communication of said circuits, and a switching relay section for operating said solenoid valve in response to a predetermined value of said output voltage of said generator so as to cause said solenoid valve to be in said first condition for vehicle speeds below a given speed that correspondings to said predetermined output voltage and whereby ignition retard is prevented by said vacuum retard unit being thereby communicated to said atmospheric pressure circuit and the throttle valve of said mechanism is fully closed when said vehicle accelerator is fully released, and so as to cause said valve to be in said second condition for vehicle speeds above that corresponding to said predetermined output voltage, to reduce said given speed so that during vehicle deceleration from speeds above said given speed the vacuum produced in said vacuum circuit and communicated as aforesaid to said vacuum retard unit causes ignition retard while the said communication of the throttle valve mechanism to said atmospheric pressure circuit prevents said throttle valve from full closure, thereby substantially reducing nixious gases generated particularly during vehicle deceleration, said switching relay section comprising a power transistor having a collector-emitter circuit connected in series with said solenoid valve, a bias resistor a second transistor having a collector-emitter circuit connected in series with said bias resistor and responsive to said predetermined value of said output voltage of said generator, and a constant-voltage element having a predetermined operating voltage and connected between the base of said power transistor and the collector of said second transistor, wherein said switching relay section further comprises a third transistor having a collector-emitter circuit connected across the base-emitter circuit of said power transistor through said constant-voltage element, a second constant-voltage element connected to the base of said third transistor and having an operating voltage higher than that of the first mentioned constant-voltage element, a second bias resistor and a first diode, said second constant-voltage element being connected in series with said second bias resistor to the collector of said power transistor and also being connected in series with said first diode to the collector of said second transistor there being a second diode connected between the collector of said second transistor and said first mentioned constantvoltage element. 